In a lever-type hoist and traction apparatus provided with an operation lever, as disclosed in for example Japanese Utility Model Application Laid-Open No. Hei 3-107490, the disclosure of which is hereby incorporated by reference, a driving shaft is provided with a driving member having teeth on its outer periphery screwed therein. In addition, said operation lever is provided with a feed click engaged with said teeth of said driving member so as to be switched over, a click portion on the feed side of the driving member being engaged with the teeth and the operation lever being reciprocally operated to forwardly screw the driving member, whereby operating a mechanical brake, a driving power due to a reciprocal operation of the operation lever being transmitted to a load-sheave from said driving shaft through said mechanical brake, and the load-sheave being driven to conduct a hoist and traction of loads. Furthermore, a click portion on the return side of the feed click is engaged with the teeth of the driving member to reciprocally operate the operation lever, whereby rearwardly screwing the driving member and thus releasing the operation of the mechanical brake to reversely rotate the load-sheave by a quantity rearwardly screwed of the driving member in order to unload or release a traction.
However, in said lever-type hoist and traction apparatus having the above described construction, the driving member is adapted to be regularly and reversely rotated by engaging one of the portion on the feed side and the return side of the feed click provided on the operation lever with the teeth provided on said outer periphery of the driving member and reciprocally operating the operation lever and the driving member is forwardly screwed by this regular rotation to operate the mechanical brake and transmit the driving power due to the reciprocal operation of the operation lever to the load-sheave from the driving shaft, whereby driving the load-sheave to be rotated, so that a disadvantage occurs in that in the case where no load is applied to the load-sheave, the driving member is forwardly screwed to operate the mechanical brake and consequently, even though the operation lever is reciprocally operated under this condition, the driving power is transmitted by a going movement of the operation lever and the operation lever is returned to a going movement-starting position without being followed by the driving member by a returning movement of the operation lever but in the case where the operation lever is reciprocally operated to operate the load-sheave in the hoist.multidot.traction direction under a no-load condition where no load is applied to the load-sheave, no-load is applied to the load-sheave, so that, even though the mechanical brake is operated during said going movement of the operation lever, an engaging resistance of the feed click engaged with the teeth of the driving member overcomes a reverse rotation resistance of the driving member to reversely rotate the mechanical brake with being accompanied by said returning movement of the operation lever, whereby releasing the mechanical brake and as a result, even though the operation lever is reciprocally operated, the driving member merely repeats the forward screwing rearward screwing and thus the mechanical brake is not operated.
So, conventionally, the operation lever is reciprocally operated with applying a load to the load-sheave or a load-chain laid on the load-sheave during the hoist.multidot.traction by means of the operation lever under the above described no-load condition or an external force is manually applied to the driving member from outside to prevent the driving member from being reversely rotated with being followed by the returning movement of the operation lever.
However, in every case, a defect occurs in that an operation for applying a load to the load-sheave or said load-chain or an operation for applying said external force to the driving member is required in addition to the reciprocal operation of the operation lever, in particular in one-man working, an operation for adding the external force by one hand with operating the operation lever by the other hand and an operation for holding a hoist and traction apparatus body must be conducted and thus the hoist and traction operation under a no-load condition is complicated.